Add a function that searches for a possible conflicting (i. e. overlaying loop
device).
Signed-off-by: Stanislav Brabec <sbrabec@xxxxxxx>
---
include/loopdev.h | 3 +++
lib/loopdev.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 58 insertions(+)
diff --git a/include/loopdev.h b/include/loopdev.h
index 57fcc1b..706388e 100644
--- a/include/loopdev.h
+++ b/include/loopdev.h
@@ -188,6 +188,9 @@ extern int loopcxt_find_by_backing_file(struct loopdev_cxt *lc,
const char *filename,
uint64_t offset, uint64_t sizelimit,
int flags);
+extern int loopcxt_check_conflict(struct loopdev_cxt *lc,
+ const char *filename,
+ uint64_t offset, uint64_t sizelimit);
extern int loopcxt_is_used(struct loopdev_cxt *lc,
struct stat *st,
diff --git a/lib/loopdev.c b/lib/loopdev.c
index 2db80fc..4606003 100644
--- a/lib/loopdev.c
+++ b/lib/loopdev.c
@@ -1566,6 +1566,61 @@ int loopcxt_find_by_backing_file(struct loopdev_cxt *lc, const char *filename,
}
/*
+ * Returns: 0 = conflict, < 0 error, 1 no conflicting device
+ */
+int loopcxt_check_conflict(struct loopdev_cxt *lc, const char *filename,
+ uint64_t offset, uint64_t sizelimit)
+{
+ int rc, hasst;
+ struct stat st;
+
+ if (!filename)
+ return -EINVAL;
+
+ hasst = !stat(filename, &st);
+
+ rc = loopcxt_init_iterator(lc, LOOPITER_FL_USED);
+ if (rc)
+ return rc;
+
+ while ((rc = loopcxt_next(lc)) == 0) {
+ uint64_t lc_sizelimit, lc_offset;
+
+ rc = loopcxt_is_used(lc, hasst ? &st : NULL,
+ filename, offset, sizelimit, 0);
+ if (!rc)
+ continue;
+ if (rc != 1)
+ break;
+ DBG(CXT, ul_debugobj(lc, "found %s backed by %s",
+ loopcxt_get_device(lc), filename));
+ rc = loopcxt_get_offset(lc, &lc_offset);
+ if (rc) {
+ DBG(CXT, ul_debugobj(lc, "failed to get offset for device %s",
+ loopcxt_get_device(lc)));
+ break;
+ }
+ rc = loopcxt_get_sizelimit(lc, &lc_sizelimit);
+ if (rc) {
+ DBG(CXT, ul_debugobj(lc, "failed to get sizelimit for device %s",
+ loopcxt_get_device(lc)));
+ break;
+ }
+
+ if (lc_sizelimit != 0 && offset >= lc_offset + lc_sizelimit)
+ continue;
+ if (sizelimit != 0 && offset + sizelimit <= lc_offset)
+ continue;
+ DBG(CXT, ul_debugobj(lc, "overlapping loop device %s",
+ loopcxt_get_device(lc)));
+ rc = 0;
+ break;
+ }
+ loopcxt_deinit_iterator(lc);
+ return rc;
+}
+
+/*
* Returns allocated string with device name
*/
char *loopdev_find_by_backing_file(const char *filename, uint64_t offset, uint64_t sizelimit, int flags)
--
2.9.0
--
Best Regards / S pozdravem,
Stanislav Brabec
software developer
---------------------------------------------------------------------
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Křižíkova 148/34 (Corso IIa) tel: +49 911 7405384547
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